Circuit breaker



2 Sheeis-Sheet 1 May 26, 1970 K. STEGMULLER CIRCUIT BREAKER Filed April 25, 1968 SE M 2 m m w m .2 4 M J} N N @E m m/ m 3 Q l v i 1% W M m Y p B m v m K 1 r 22$ ATTORNEYS.

May 26, 1970 K. STEGMULLER 3,514,553

CIRCUIT BREAKER Filed April 25, 1968 2 Sheets-Sheet 2 FIG. 4

' INVENTOR Karl Sregmuller I ywu/ A ORNEYS.

United States Patent 3,514,563 CIRCUIT BREAKER Karl Stegmiiller, Regensburg, Germany, assignor to Sachsenwerk, Lichtuud Kraft-Aktiengesellschaft, Munich, Germany Filed Apr. 25, 1968, Ser. No. 723,980 Claims priority, applicatitar; gle'many, Apr. 28, 1967,

Int. Cl. rloih 33/68 US. Cl. 200-150 5 Claims ABSTRACT OF THE DISCLOSURE BACKGROUND OF THE INVENTION The present invention relates to a circuit breaker and more particularly to a circuit breaker having transverse channels provided with a narrow portion near a movable contact element.

The operating principle of such circuit breakers is that an electric are drawn in the arcing chamber, during separation of contact elements, evaporates arc quenching fluid provided in the arcing chamber. The evaporated quenching fluid creates a pressure which is utilized to force quenching fluid through transverse channels also provided in the circuit breaker. According to such devices, the openings to the transverse channels are consecutively opened by a movable contact element, which is moved by pressure created in the arcing chamber. As each transverse channel is opened, a path connecting the arcing chamber to a remote pressure-equalization chamber or compartment is opened. In such devices, the first transverse channel is spaced from a stationary contact element according to the quenching distance required. In other words, the quenching distance depends on the distance between two contact elements required to first extinguish an electric arc. Until the first transverse channel is opened, the power generated by the arc drawn creates pressures in the pressure chamber which can reach dangerous levels, particularly where high voltages and high currents are involved. Therefore, the art has concerned itself with providing an effective prerelease means or arrangement whereby such dangerous power levels are reduced or attenuated to a less dangerous level.

One such prerelease arrangement would have the pressure chamber of the device designed to include a lateral opening which remains open regardless of the position of the movable contact element in the device. Such an opening, which cannot be closed off by the movable contact element provides a channel through which gases generated by an are drawn through the quenching fluid are released to a pressure-free or equalization zone. This arrangement, however, has the disadvantage that the discharge of the gases is asymmetrical to the stationary contact element in the device thus bringing about the result that an electric are drawn in the device remains in the area of the lateral discharge opening thus provided. Consequently, considerable burning results on one side of the device. This condition, in turn, leads to premature 3,514,563 Patented May 26, 1970 ice Wear of the contact element. Moreover, the physical durab1l1ty of the circuit breaker itself is considerably reduced.

SUMMARY OF THE INVENTION It is, therefore, an object of this invention to provide an improved circuit breaker which eliminates the abovedescribed disadvantages of similar prior-art devices.

In brief, the present invention relates to a circuit breaker having a pressure chamber provided therein, which is connected to a pressure-equalization chamber during the period before the movable contact opens the first transverse channels. This is accomplished by providing a gas prerelease means wherein an axial blind bore is provided within the movable contact and a lateral opening is provided in the movable contact which leads from the blind bore to the outside of the movable contact and to the pressure-equalization chamber.

The primary advantage of the present invention is the uniform burning of the contact elements in the device. This advantage is achieved without a reduction in the mechanical or physical durability of the circuit breaker. An additional advantage is realized when the switch is used to start a current flow. The quenching fluid present in the pressure chamber flows off through the blind bore and lateral opening in the movable contact in accordance with the volume capacity of such contact. Thus, a pressure of several atmospheres is created in the pressure chamber which increases the breakdown resistance of the quenching fluid. As a result, a desirable shortening of the arc length is realized.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a longitudinal sectional view taken along the line 11 of FIG. 2 of a portion of the circuit breaker according to the invention.

. FIG. 2 is a cross-sectional view taken along the line 2-2 of FIG. 1.

FIG. 3 is a cross-sectional View taken along the line 33 of FIG. 1.

FIG. 4 is a sectional view of a portion of another embodiment of the movable contact element, according to the invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring now to FIGS. 1, 2 and 3, the circuit breaker has a stationary contact 1 and a movable pin or contact 2 which is movable away from stationary contact 1. The movable contact 2 includes a blind bore 3 and a lateral opening 4 leading from the blind bore 3. A narrow portion 5 is provided near the movable contact 2 and is of such size that the transverse channels 6, 7, 8 and 9, respectively, are not completely blocked by the movable contact 2. The transverse channels 6, 7, 8 and 9 have their respective discharge ends alternately oifset with respect to each other, as best illustrated in FIGS. 2 and 3. Each of the transverse channels opens into one of the longitudinal channels or zones 10 and 11 which form part of the pressure-equalization chamber means. Part of the pressure-equalization means (not shown) is disposed above the stationary switching element 1. The longitudinal channels 10 and 11 extend generally parallel to the longitudinal direction of movement of the movable contact 2. The stationary contact element 1 is positioned in an arcing chamber 12. which is confined on all sides except where the passage 16 communicates therewith. The movable contact 2 is movably disposed within passage 16. The arcing chamber 12 forms the pressure space of the circuit breaker.

During separation of the movable contact 2 from stationary contact 1, pressure is built up in the arcing chamber 12 due to evaporation of quenching fluid provided therein by the electric are 13 formed as a result of such separation. This pressure, particularly in high-voltage switches, can range extremely high, especially when an excess or short-circuit current is to be interrupted. It is necessary to relieve such extraordinarily high pressure loads on the circuit breaker without requiring heavy equipment and/or high costs associated with special circuit breaker constructions. Accordingly, the present invention provides an arrangement for allowing the preliminary flow of gas, formed upon arcing, from the arcing chamber of the device. Such a prerelease arrangement operates to relieve some of the excess pressure in the arcing chamber 12 until such time that the first transverse channel 6 is opened by movable contact 2. The pressure load in arcing chamber 12 is relieved via the blind bore 3, the lateral opening 4, and the gap a, provided between movable contact 2 and the narrow portion 5 of the transverse-flow channels, and through the longitudinal channels and 11 of the pressure-equalization chamber.

The blind bore 3 can also be provided with an additional lateral opening 14, as shown in FIG. 4. In such an arrangement, the gases created at the switching element or, at least a portion of such gases, can flow directly into the pressure-equalization chamber.

Upon the transverse channels 6, 7, 8 and 9 being successively opened by movement of the movable contact 2, additional oil is made available to flow into arcing chamber 12 and around the electric are 13. Immediately following the extinction of the arc 13, the breakdown strength of the contact circuit is favorably affected. The lateral openings 4 and 14 are of such length that during the period when the transverse channels are cut off from the pressure chamber 12 by movable contact 2, at least one transverse channel is disposed oppositely with respect to the lateral opening. Thus constructed, the arcing chamber 12 is in continuous communication with the pressureequalization chamber, either by way of the lateral openings 4 and 14, or, by movement of the movable contact 2 beyond the first transverse channel 6. Of course, it is not necessary that the lateral openings 4 and 14 be provided the same dimensions. Rather, the dimensions of each particular lateral opening depend upon the amount of pressure reduction desired to be attained.

In addition to the use of the gas pressure created by the arc to cause the flow of quenching fluid through the transverse channels, the quenching fluid can be forced to flow through the transverse channels. This is accomplished, for example, by the quenching fluid displaced,

. by the action of movable contact 2 as it moves away from stationary contact 1, being delivered to transverse channels via a channel 15. Small currents whose arcs are not suflicient to create adequate pressure to cause intensive oil flow around the arc can satisfactorily be quenched or interrupted by this forced quenching fluid flow.

It will thus be seen that, in accordance with the present invention, there are provided means which form the pressure-equalization chamber, the latter including at least the longitudinal channels 10 or 11, which extend generally parallel to the longitudinal direction of movement of the movable contact 2. The transverse channels 6, 7, 8, and 9 are formed in a channel means, as best seen in FIG. 1, and are spaced from each other in a longitudinal direction. Each of the transverse channels communicates with one of the longitudinal channels and includes a narrow portion 5 located at a point spaced from where the respective transverse channels 6, 7, 8 and 9 communicates with the respective longitudinal channel, 10 or 11. The narrow portions 5 of each transverse channel are aligned with respect to each other and also with longitudinal passage 16 formed in the channel means. The movable contact 2 is disposed in the longitudinal passage 16 for movement therethrough during opening and closing of the circuit breaker. As the movable contact 2 moves away, from stationary contact 1, successive ones of the transverse chan- 4 nels are unblocked to place the arcing chamber 12 in communication with longitudinal channels 10 or 11, respectively.

It will also be seen that the movable contact 2 has a longitudinal blind bore 3 and a lateral opening 4 which communicates with bore 3. Upon separation of the contacts, the bore 3 and opening 4 together establish communication between the arcing chamber 12 and one of the longitudinal channel 10 or 11 via at least one of the transverse channels 6, 7, 8 or 9 prior to the time the first of the successive transverse channels 6, 7, 8 and 9 is unblocked by movable contact 2. This arrangement allows the preliminary flow of gas formed upon arcing through at least one of the transverse channels into a longitudinal channel and thereby prevents excessive pressure buildup in the arcing chamber.

While a circuit breaker like that of the present invention is known, wherein a movable contact is provided with an axial blind bore and lateral openings, such a prior-art device is not provided transverse channels and, indeed, the blind bore with its lateral openings serves an altogether different purpose. In such prior'art device, the pressure created by an electric arc moves a differential piston which presses quenching fluid through a stationary bell-shaped contact into the blind bore of a movable contact. The quenching fluid, thus forced through the blind bore, flows through the lateral opening leading from the blind bore and, from there, is returned to the arcing chamber. Such a device does not contemplate nor does it intend to provide a pressure relieving arrangement as in the present invention and should, therefore, not be confused with a circuit breaker according to the present invention.

It will be understood that the above description of the present invention is susceptible to various modifications, changes and adaptations, and the same are intended to be comprehended within the meaning and range of equivalents of the appended claims.

I claim:

1. A circuit breaker comprising, in combination:

(a) a stationary contact and a movable contact mounted for movement in a longitudinal direction toward and away from said stationary contact;

(b) means forming an arcing chamber within which there is formed an arc occurring upon movement of said movable contact away from said stationary contact;

(c) means forming a pressure-equalization chamber,

said means including at least one longitudinal channel which extends generally parallel to said longitudinal direction of movement of said movable contact;

(d) channel means forming a plurality of transverse channels communicating with said longitudinal channel, said transverse channels being spaced from each other in longitudinal direction, each of said transverse channels having, at a point spaced from where the respective transverse channel communicates with said longitudinal channel, a narrow portion and the narrow portions of said transverse channels being aligned with each other, said channel means further forming, in alignment with said narrowed portions, a longitudinal passage within which said movable contact is arranged for movement during opening and closing of the circuit breaker, in consequence of which when said movable contact moves away from said stationary contact, successive ones of said transverse channels are unblocked and place said arcing chamber in communication with said longitudinal channel;

(e) said movable contact having a longitudinal blind 'bore and a lateral opening which communicates with said bore, said bore and opening together, upon separation of said contacts, establishing communication between said arcing chamber and said longitudinal channel via at least one of said transverse channels prior to the time the first of said successive transverse channels is unblocked by said movable contact,

thereby to allow the preliminary flow of gas formed upon arcing through at least one of said transverse channels into said longitudinal channel and thus preventing excessive pressure buildup in said arcing chamber.

2. The combination defined in claim 1 wherein said lateral opening extends in longitudinal direction a length sulficient to establish a communication between said arcing chamber and at least one of said transverse channels continuously until at least the instant the first of said transverse channels is unblocked by said movable contact.

3. The combination defined in claim 1 wherein each of said transverse channels has an inlet which is located on that side of said longitudinal passage which is opposite the side on which said longitudinal channel is located, wherein the inner surface of said channel means which defines said passage and the outer surface of said movable contact are spaced from each other and thus form a gap between themselves, and wherein said lateral opening is directed toward the inlet side of said transverse channels, 20

in consequence of which communication between said are chamber and said longitudinal channel is established through said gap.

4. The combination defined in claim 3 wherein said movable contact is provided with a second lateral opening which also communicates with said bore and which is located opposite the first-mentioned lateral opening.

5. The combination defined in claim 1 wherein said means (c) include two longitudinal channels and wherein said transverse channels communicate, alternately, with said two longitudinal channels.

References Cited UNITED STATES PATENTS 1,016,796 10/1957 Germany.

ROBERT S. MACON, Primary Examiner 

